Improvement in pipe-elbows



UNITED STATES PATENT OFFICE.

GEORGE LUPTON, OF INDIANAPOLIS, INDIANA.

IMPRovEMENT IN PIPE-ELBows.

Specication forming part of Letters Patent No. 154,760, dated September8,1874; application filed l January 6, 1874.

To all whom it may concern:

Be it known that I, GEORGE LUPToN, of Indianapolis, in the county ofMarion and State of Indiana, have invented certain Improvements in th eConstruction of Pipe-Elbows from Sheet Metal, of which the following isa specication The nature of my invention consists in providing a smoothcurved pipe of uniform thickness throughout, and composed of a singleuncrimped and uncut piece of sheet-iron. I have contemplated variousprocesses by which such a curved pipe may be produced from such a singlepiece of sheet-iron, and I do not propose to restrict myself to theparticular mode hereinafter described, for my invention includes everycurved pipe possessing` the abovestated peculiarities, no matter howproduced.

A, Figure l, is a plan of a sheet of variable thickness for one elbow.vA1 is a transverse section of the same sheet, showing double thicknessin the center, and tapering gradually to the ordinary thickness at theedges. A2, Fig. 2, shows the same sheetformed into a straight trough, ofU shape, preparatory forl the stretching and curving process. YThisstraight trough is now passed between pressure-rollers, one ofwhich isconcave and theV other convex at the periphery. These rollers stretchthe trough lengthwise in the middle, gradually reducing the thickness ofthemetal from the center to the edge to a uniform gage, and therebycurving it into the shape shown at B, Fig. 3. This curved trough is nowplaced upon a curved mandrel, whose diameter corresponds with theinterior of the desired elbow, and by means of curved dies its edges areswaged or pressed into the concave radius of the mandrel, where theseedges are securely united by rivets or seam, in the usual manner.

I am aware that in the manufacture of spouts for coffee-pots made ofsheet metal the practice has been to first make a complete straightpipe, and give to it the requisite slight curve at one end by bending itover a flexible mandrel. must necessarily be stretched and thinned outalong the convex side of the bend, and, as the pipe was originally made.of metal of even thickness, the curve will, when finished, be ofvariable thickness. Besides, in practice, the concave side of the bendalways becomes solnewhat crimped. Persons skilled in the art ofmetal-working will at once recognize the impossibility of making acurved-pipe such as I have described by such a process. I am also awarethat cast pipes of soft metal have been made in straight sections withthickened portions, by thinning out which the pipe was curved, and itswalls left of uniform thickness throughout.

By the employment of this known process and the machinery used topractice it, it is also impossible to make an elbow of sheetiron such asI have described. Thus, in the state of the art before my invention,there was neither any known means by using which a curved pipe of sheetiron of the character stated might have been made, norwas ever such apipe made, in fact.

I claim- A stove-pipe elbow made from a blank of sheet-iron having asingle longitudinal seam, and formed Without crimping or cutting, thuspresenting a smooth surface of uniform thickness throughout wheninished, substantially as specied.

GEORGE LUPTON.

Witnesses:

WILLTAM J. McCULLoUGH, LEWIs SHIRELY.

By this rprocess the metal'

